feature: add argument parsing and setup.py file for cli tool capability

setup.py

@@ -0,0 +1,31 @@
+from setuptools import setup, find_packages
+
+setup(
+    name='markitdown',
+    version='0.1.0',
+    package_dir={'': 'src'},
+    packages=find_packages(where='src'),
+    install_requires=[
+        'mammoth',
+        'markdownify',
+        'pandas',
+        'pdfminer.six',
+        'python-pptx',
+        'puremagic',
+        'requests',
+        'beautifulsoup4',
+        'pydub',
+        'SpeechRecognition',
+        'youtube_transcript_api',
+    ],
+    entry_points={
+        'console_scripts': [
+            'markitdown=markitdown.__main__:main',
+        ],
+    },
+    author='Adam Fourney',
+    author_email='adamfo@microsoft.com',
+    description='Convert various file formats to markdown',
+    license='MIT',
+    python_requires='>=3.6',
+)

src/markitdown/__main__.py

@@ -2,21 +2,15 @@
 #
 # SPDX-License-Identifier: MIT
 import sys
+import argparse
 from ._markitdown import MarkItDown
 
 
 def main():
-    if len(sys.argv) == 1:
-        markitdown = MarkItDown()
-        result = markitdown.convert_stream(sys.stdin.buffer)
-        print(result.text_content)
-    elif len(sys.argv) == 2:
-        markitdown = MarkItDown()
-        result = markitdown.convert(sys.argv[1])
-        print(result.text_content)
-    else:
-        sys.stderr.write(
-            """
+    parser = argparse.ArgumentParser(
+        description='Convert various file formats to markdown.',
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        usage="""
 SYNTAX: 
     
     markitdown <OPTIONAL: FILENAME>
@@ -34,9 +28,20 @@ EXAMPLE:
 
     markitdown < example.pdf
 """.strip()
-            + "\n"
-        )
+    )
+
+    parser.add_argument('filename', nargs='?')
+    args = parser.parse_args()
+
+    if args.filename is None:
+        markitdown = MarkItDown()
+        result = markitdown.convert_stream(sys.stdin.buffer)
+        print(result.text_content)
+    else:
+        markitdown = MarkItDown()
+        result = markitdown.convert(args.filename)
+        print(result.text_content)
 
 
 if __name__ == "__main__":
-    main()
+    main()